There is conventionally known a fixing device, provided in an electrophotographic image-forming device, including a heating assembly for heating recording sheets, a roller facing the heating assembly to nip recording sheets with the roller, and a frame for supporting both the heating assembly and the roller. The frame in this fixing device has a pair of guides for holding the heating assembly in position, with a guided portion of each guide provided on each side of the heating assembly relative to a conveying direction of the recording sheets. The pair of guides serves to fix the position of the heating assembly in the conveying direction and also serves to guide movement of the heating assembly when the heating assembly is moved toward and away from the roller.